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Heo J, Park YJ, Kim Y, Lee HS, Kim J, Kwon SH, Kang MG, Rhee HW, Sun W, Lee JH, Cho H. Mitochondrial E3 ligase MARCH5 is a safeguard against DNA-PKcs-mediated immune signaling in mitochondria-damaged cells. Cell Death Dis 2023; 14:788. [PMID: 38040710 PMCID: PMC10692114 DOI: 10.1038/s41419-023-06315-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/03/2023]
Abstract
Mitochondrial dysfunction is important in various chronic degenerative disorders, and aberrant immune responses elicited by cytoplasmic mitochondrial DNA (mtDNA) may be related. Here, we developed mtDNA-targeted MTERF1-FokI and TFAM-FokI endonuclease systems to induce mitochondrial DNA double-strand breaks (mtDSBs). In these cells, the mtDNA copy number was significantly reduced upon mtDSB induction. Interestingly, in cGAS knockout cells, synthesis of interferon β1 and interferon-stimulated gene was increased upon mtDSB induction. We found that mtDSBs activated DNA-PKcs and HSPA8 in a VDAC1-dependent manner. Importantly, the mitochondrial E3 ligase MARCH5 bound active DNA-PKcs in cells with mtDSBs and reduced the type І interferon response through the degradation of DNA-PKcs. Likewise, mitochondrial damage caused by LPS treatment in RAW264.7 macrophage cells increased phospho-HSPA8 levels and the synthesis of mIFNB1 mRNA in a DNA-PKcs-dependent manner. Accordingly, in March5 knockout macrophages, phospho-HSPA8 levels and the synthesis of mIFNB1 mRNA were prolonged after LPS stimulation. Together, cytoplasmic mtDNA elicits a cellular immune response through DNA-PKcs, and mitochondrial MARCH5 may be a safeguard to prevent persistent inflammatory reactions.
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Affiliation(s)
- June Heo
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, South Korea
- Department of Biomedical Sciences, Graduate School of Ajou University, Suwon, South Korea
| | - Yeon-Ji Park
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, South Korea
| | - Yonghyeon Kim
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, South Korea
- Department of Biomedical Sciences, Graduate School of Ajou University, Suwon, South Korea
| | - Ho-Soo Lee
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, South Korea
| | - Jeongah Kim
- Department of Anatomy, College of medicine, Korea University, Seoul, South Korea
| | - Soon-Hwan Kwon
- Department of Infectious Diseases, Research Center of Infectious and Environmental Diseases, Armed Forces Medical Research Institute, Daejeon, South Korea
| | - Myeong-Gyun Kang
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - Hyun-Woo Rhee
- Department of Chemistry, Seoul National University, Seoul, South Korea
| | - Woong Sun
- Department of Anatomy, College of medicine, Korea University, Seoul, South Korea
| | - Jae-Ho Lee
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, South Korea.
- Department of Biomedical Sciences, Graduate School of Ajou University, Suwon, South Korea.
| | - Hyeseong Cho
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, South Korea.
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2
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González-Arzola K, Díaz-Quintana A. Mitochondrial Factors in the Cell Nucleus. Int J Mol Sci 2023; 24:13656. [PMID: 37686461 PMCID: PMC10563088 DOI: 10.3390/ijms241713656] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/31/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
The origin of eukaryotic organisms involved the integration of mitochondria into the ancestor cell, with a massive gene transfer from the original proteobacterium to the host nucleus. Thus, mitochondrial performance relies on a mosaic of nuclear gene products from a variety of genomes. The concerted regulation of their synthesis is necessary for metabolic housekeeping and stress response. This governance involves crosstalk between mitochondrial, cytoplasmic, and nuclear factors. While anterograde and retrograde regulation preserve mitochondrial homeostasis, the mitochondria can modulate a wide set of nuclear genes in response to an extensive variety of conditions, whose response mechanisms often merge. In this review, we summarise how mitochondrial metabolites and proteins-encoded either in the nucleus or in the organelle-target the cell nucleus and exert different actions modulating gene expression and the chromatin state, or even causing DNA fragmentation in response to common stress conditions, such as hypoxia, oxidative stress, unfolded protein stress, and DNA damage.
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Affiliation(s)
- Katiuska González-Arzola
- Centro Andaluz de Biología Molecular y Medicina Regenerativa—CABIMER, Consejo Superior de Investigaciones Científicas—Universidad de Sevilla—Universidad Pablo de Olavide, 41092 Seville, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Seville, Spain
| | - Antonio Díaz-Quintana
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, 41012 Seville, Spain
- Instituto de Investigaciones Químicas—cicCartuja, Universidad de Sevilla—C.S.I.C, 41092 Seville, Spain
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Sasaki Y, Norikura T, Matsui-Yuasa I, Fujii R, Limantara L, Kojima-Yuasa A. Kaempferia galanga L. extract and its main component, ethyl p-methoxycinnamate, inhibit the proliferation of Ehrlich ascites tumor cells by suppressing TFAM expression. Heliyon 2023; 9:e17588. [PMID: 37408910 PMCID: PMC10319241 DOI: 10.1016/j.heliyon.2023.e17588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 07/07/2023] Open
Abstract
Kaempferia galanga L. shows anti-cancer effects; however, the underling mechanism remains unclear. In this study, we explored the underlying mechanism of the anti-cancer effects of Kaempferia galanga L. Kaempferia galanga L. rhizome extracts (KGEs) suppressed Ehrlich ascites tumor cell (EATC) proliferation by inhibiting S-phase progression. The main component of KGE is ethyl p-methoxycinnamate (EMC), which exhibits the same anti-proliferative effect as KGE. Furthermore, EMC induced the downregulation of cyclin D1 and upregulation of p21. EMC also decreased the expression of mitochondrial transcription factor A (TFAM) but did not significantly change mitochondrial DNA copy number and membrane potential. Phosphorylation at Ser62 of c-Myc, a transcription factor of TFAM, was decreased by EMC treatment, which might be due to the suppression of H-ras expression. These results indicate that EMC is the active compound responsible for the anti-cancer effect of KGE and suppresses EATC proliferation by regulating the protein expression of cyclin D1 and p21; TFAM may also regulate the expression of these genes. In addition, we investigated the anticancer effects of KGE and EMC in vivo using EATC bearing mice. The volume of ascites fluid was significantly increased by intraperitoneal administration of EATC. However, the increase in the volume of ascites fluid was suppressed by oral administration of EMC and KGE. This study provides novel insights into the association between the anti-cancer effects of natural compounds and TFAM, indicating that TFAM might be a potential therapeutic target.
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Affiliation(s)
- Yutaro Sasaki
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Osaka, 558-8585, Japan
| | - Toshio Norikura
- Department of Nutrition, Aomori University of Health and Welfare, Aomori, 030-8505, Japan
| | - Isao Matsui-Yuasa
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Osaka, 558-8585, Japan
- Department of Nutrition, Graduate School of Human Life and Ecology, Osaka Metropolitan University, Osaka, 558-8585, Japan
| | - Ritsuko Fujii
- Research Center for Artificial Photosynthesis, Osaka Metropolitan University, Osaka, 558-8585, Japan
| | - Leenawaty Limantara
- Center for Urban Studies, Universitas Pembangunan Jaya, 15413, Banten, Indonesia
| | - Akiko Kojima-Yuasa
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Osaka, 558-8585, Japan
- Department of Nutrition, Graduate School of Human Life and Ecology, Osaka Metropolitan University, Osaka, 558-8585, Japan
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Erturk E, Enes Onur O, Akgun O, Tuna G, Yildiz Y, Ari F. Mitochondrial miRNAs (MitomiRs): Their potential roles in breast and other cancers. Mitochondrion 2022; 66:74-81. [PMID: 35963496 DOI: 10.1016/j.mito.2022.08.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/19/2022] [Accepted: 08/02/2022] [Indexed: 11/15/2022]
Abstract
Breast cancer is the most common cancer in women worldwide. MicroRNAs (miRNAs) are non-coding RNAs that are involved in the post-transcriptional regulation of gene expression. Although miRNAs mainly act in the cytoplasm, they can be found in the mitochondrial compartment of the cell. These miRNAs called "MitomiR", they can change mitochondrial functions by regulating proteins at the mitochondrial level and cause cancer. In this review, we have aimed to explain miRNA biogenesis, transport pathways to mitochondria, and summarize mitomiRs that have been shown to play an important role in mitochondrial function, especially in the initiation and progression of breast cancer.
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Affiliation(s)
- Elif Erturk
- Bursa Uludag University, Vocational School of Health Services, 16059, Bursa, Turkey
| | - Omer Enes Onur
- Bursa Uludag University, Department of Biology, Science and Art Faculty, 16059, Bursa, Turkey
| | - Oguzhan Akgun
- Bursa Uludag University, Department of Biology, Science and Art Faculty, 16059, Bursa, Turkey
| | - Gonca Tuna
- Bursa Uludag University, Department of Biology, Science and Art Faculty, 16059, Bursa, Turkey
| | - Yaren Yildiz
- Bursa Uludag University, Department of Biology, Science and Art Faculty, 16059, Bursa, Turkey
| | - Ferda Ari
- Bursa Uludag University, Department of Biology, Science and Art Faculty, 16059, Bursa, Turkey.
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MitomiRs: their roles in mitochondria and importance in cancer cell metabolism. Radiol Oncol 2021; 55:379-392. [PMID: 34821131 PMCID: PMC8647792 DOI: 10.2478/raon-2021-0042] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 09/28/2021] [Indexed: 11/21/2022] Open
Abstract
Background MicroRNAs (miRNAs) are short non-coding RNAs that play important roles in almost all biological pathways. They regulate post-transcriptional gene expression by binding to the 3’untranslated region (3’UTR) of messenger RNAs (mRNAs). MitomiRs are miRNAs of nuclear or mitochondrial origin that are localized in mitochondria and have a crucial role in regulation of mitochondrial function and metabolism. In eukaryotes, mitochondria are the major sites of oxidative metabolism of sugars, lipids, amino acids, and other bio-macromolecules. They are also the main sites of adenosine triphosphate (ATP) production. Conclusions In the review, we discuss the role of mitomiRs in mitochondria and introduce currently well studied mitomiRs, their target genes and functions. We also discuss their role in cancer initiation and progression through the regulation of mRNA expression in mitochondria. MitomiRs directly target key molecules such as transporters or enzymes in cell metabolism and regulate several oncogenic signaling pathways. They also play an important role in the Warburg effect, which is vital for cancer cells to maintain their proliferative potential. In addition, we discuss how they indirectly upregulate hexokinase 2 (HK2), an enzyme involved in glucose phosphorylation, and thus may affect energy metabolism in breast cancer cells. In tumor tissues such as breast cancer and head and neck tumors, the expression of one of the mitomiRs (miR-210) correlates with hypoxia gene signatures, suggesting a direct link between mitomiR expression and hypoxia in cancer. The miR-17/92 cluster has been shown to act as a key factor in metabolic reprogramming of tumors by regulating glycolytic and mitochondrial metabolism. This cluster is deregulated in B-cell lymphomas, B-cell chronic lymphocytic leukemia, acute myeloid leukemia, and T-cell lymphomas, and is particularly overexpressed in several other cancers. Based on the current knowledge, we can conclude that there is a large number of miRNAs present in mitochondria, termed mitomiR, and that they are important regulators of mitochondrial function. Therefore, mitomiRs are important players in the metabolism of cancer cells, which need to be further investigated in order to develop a potential new therapies for cancer.
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6
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Bloom syndrome DNA helicase deficiency is associated with oxidative stress and mitochondrial network changes. Sci Rep 2021; 11:2157. [PMID: 33495511 PMCID: PMC7835382 DOI: 10.1038/s41598-021-81075-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 12/30/2020] [Indexed: 01/03/2023] Open
Abstract
Bloom Syndrome (BS; OMIM #210900; ORPHA #125) is a rare genetic disorder that is associated with growth deficits, compromised immune system, insulin resistance, genome instability and extraordinary predisposition to cancer. Most efforts thus far have focused on understanding the role of the Bloom syndrome DNA helicase BLM as a recombination factor in maintaining genome stability and suppressing cancer. Here, we observed increased levels of reactive oxygen species (ROS) and DNA base damage in BLM-deficient cells, as well as oxidative-stress-dependent reduction in DNA replication speed. BLM-deficient cells exhibited increased mitochondrial mass, upregulation of mitochondrial transcription factor A (TFAM), higher ATP levels and increased respiratory reserve capacity. Cyclin B1, which acts in complex with cyclin-dependent kinase CDK1 to regulate mitotic entry and associated mitochondrial fission by phosphorylating mitochondrial fission protein Drp1, fails to be fully degraded in BLM-deficient cells and shows unscheduled expression in G1 phase cells. This failure to degrade cyclin B1 is accompanied by increased levels and persistent activation of Drp1 throughout mitosis and into G1 phase as well as mitochondrial fragmentation. This study identifies mitochondria-associated abnormalities in Bloom syndrome patient-derived and BLM-knockout cells and we discuss how these abnormalities may contribute to Bloom syndrome.
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Basu U, Bostwick AM, Das K, Dittenhafer-Reed KE, Patel SS. Structure, mechanism, and regulation of mitochondrial DNA transcription initiation. J Biol Chem 2020; 295:18406-18425. [PMID: 33127643 PMCID: PMC7939475 DOI: 10.1074/jbc.rev120.011202] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 10/29/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are specialized compartments that produce requisite ATP to fuel cellular functions and serve as centers of metabolite processing, cellular signaling, and apoptosis. To accomplish these roles, mitochondria rely on the genetic information in their small genome (mitochondrial DNA) and the nucleus. A growing appreciation for mitochondria's role in a myriad of human diseases, including inherited genetic disorders, degenerative diseases, inflammation, and cancer, has fueled the study of biochemical mechanisms that control mitochondrial function. The mitochondrial transcriptional machinery is different from nuclear machinery. The in vitro re-constituted transcriptional complexes of Saccharomyces cerevisiae (yeast) and humans, aided with high-resolution structures and biochemical characterizations, have provided a deeper understanding of the mechanism and regulation of mitochondrial DNA transcription. In this review, we will discuss recent advances in the structure and mechanism of mitochondrial transcription initiation. We will follow up with recent discoveries and formative findings regarding the regulatory events that control mitochondrial DNA transcription, focusing on those involved in cross-talk between the mitochondria and nucleus.
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Affiliation(s)
- Urmimala Basu
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; Graduate School of Biomedical Sciences, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | | | - Kalyan Das
- Department of Microbiology, Immunology, and Transplantation, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | | | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA.
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8
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Sharma P, Bharat, Dogra N, Singh S. Small Regulatory Molecules Acting Big in Cancer: Potential Role of Mito-miRs in Cancer. Curr Mol Med 2020; 19:621-631. [PMID: 31340735 DOI: 10.2174/1566524019666190723165357] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 07/08/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022]
Abstract
MicroRNAs [miRNAs] are short, non-coding, single stranded RNA molecules regulating gene expression of their targets at the posttranscriptional level by either degrading mRNA or by inhibiting translation. Previously, miRNAs have been reported to be present inside the mitochondria and these miRNAs have been termed as mito-miRs. Origin of these mito-miRs may either be from mitochondrial genome or import from nucleus. The second class of mito-miRs makes it important to unravel the involvement of miRNAs in crosstalk between nucleus and mitochondria. Since miRNAs are involved in various physiological processes, their deregulation is often associated with disease progression, including cancer. The current review focuses on the involvement of miRNAs in different mitochondrial mediated processes. It also highlights the importance of exploring the interaction of miRNAs with mitochondrial genome, which may lead to the development of small regulatory RNA based therapeutic options.
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Affiliation(s)
- Praveen Sharma
- Laboratory of Molecular Medicine, Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Mansa Road, Bathinda 151001, Punjab, India
| | - Bharat
- Laboratory of Molecular Medicine, Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Mansa Road, Bathinda 151001, Punjab, India
| | - Nilambra Dogra
- Centre for Systems Biology and Bioinformatics, Panjab University, Sector-25, Chandigarh 160014, India
| | - Sandeep Singh
- Laboratory of Molecular Medicine, Department of Human Genetics and Molecular Medicine, School of Health Sciences, Central University of Punjab, Mansa Road, Bathinda 151001, Punjab, India
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9
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Vozáriková V, Kunová N, Bauer JA, Frankovský J, Kotrasová V, Procházková K, Džugasová V, Kutejová E, Pevala V, Nosek J, Tomáška Ľ. Mitochondrial HMG-Box Containing Proteins: From Biochemical Properties to the Roles in Human Diseases. Biomolecules 2020; 10:biom10081193. [PMID: 32824374 PMCID: PMC7463775 DOI: 10.3390/biom10081193] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 08/11/2020] [Accepted: 08/13/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial DNA (mtDNA) molecules are packaged into compact nucleo-protein structures called mitochondrial nucleoids (mt-nucleoids). Their compaction is mediated in part by high-mobility group (HMG)-box containing proteins (mtHMG proteins), whose additional roles include the protection of mtDNA against damage, the regulation of gene expression and the segregation of mtDNA into daughter organelles. The molecular mechanisms underlying these functions have been identified through extensive biochemical, genetic, and structural studies, particularly on yeast (Abf2) and mammalian mitochondrial transcription factor A (TFAM) mtHMG proteins. The aim of this paper is to provide a comprehensive overview of the biochemical properties of mtHMG proteins, the structural basis of their interaction with DNA, their roles in various mtDNA transactions, and the evolutionary trajectories leading to their rapid diversification. We also describe how defects in the maintenance of mtDNA in cells with dysfunctional mtHMG proteins lead to different pathologies at the cellular and organismal level.
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Affiliation(s)
- Veronika Vozáriková
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina B-1, 842 15 Bratislava, Slovakia; (V.V.); (J.F.); (K.P.); (V.D.)
| | - Nina Kunová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia; (N.K.); (J.A.B.); (V.K.); (E.K.); (V.P.)
| | - Jacob A. Bauer
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia; (N.K.); (J.A.B.); (V.K.); (E.K.); (V.P.)
| | - Ján Frankovský
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina B-1, 842 15 Bratislava, Slovakia; (V.V.); (J.F.); (K.P.); (V.D.)
| | - Veronika Kotrasová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia; (N.K.); (J.A.B.); (V.K.); (E.K.); (V.P.)
| | - Katarína Procházková
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina B-1, 842 15 Bratislava, Slovakia; (V.V.); (J.F.); (K.P.); (V.D.)
| | - Vladimíra Džugasová
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina B-1, 842 15 Bratislava, Slovakia; (V.V.); (J.F.); (K.P.); (V.D.)
| | - Eva Kutejová
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia; (N.K.); (J.A.B.); (V.K.); (E.K.); (V.P.)
| | - Vladimír Pevala
- Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia; (N.K.); (J.A.B.); (V.K.); (E.K.); (V.P.)
| | - Jozef Nosek
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina CH-1, 842 15 Bratislava, Slovakia;
| | - Ľubomír Tomáška
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina B-1, 842 15 Bratislava, Slovakia; (V.V.); (J.F.); (K.P.); (V.D.)
- Correspondence: ; Tel.: +421-2-90149-433
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Izumi H, Funa K. Telomere Function and the G-Quadruplex Formation are Regulated by hnRNP U. Cells 2019; 8:cells8050390. [PMID: 31035352 PMCID: PMC6562495 DOI: 10.3390/cells8050390] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/22/2019] [Accepted: 04/25/2019] [Indexed: 11/27/2022] Open
Abstract
We examine the role of the heterogenous ribonucleoprotein U (hnRNP U) as a G-quadruplex binding protein in human cell lines. Hypothesizing that hnRNP U is associated with telomeres, we investigate what other telomere-related functions it may have. Telomeric G-quadruplexes have been fully characterized in vitro, but until now no clear evidence of their function or in vivo interactions with proteins has been revealed in mammalian cells. Techniques used were immunoprecipitation, DNA pull-down, binding assay, and Western blots. We identified hnRNP U as a G-quadruplex binding protein. Immunoprecipitations disclosed that endogenous hnRNP U associates with telomeres, and DNA pull-downs showed that the hnRNP U C-terminus specifically binds telomeric G-quadruplexes. We have compared the effect of telomere repeat containing RNA (TERRA) on binding between hnRNP U and telomeric (Tel) or single- stranded Tel (ssTel) oligonucleotides and found that ssTel binds stronger to TERRA than to Tel. We also show that hnRNP U prevents replication protein A (RPA) accumulation at telomeres, and the recognition of telomeric ends by hnRNP suggests that a G-quadruplex promoting protein regulates its accessibility. Thus, hnRNP U-mediated formation has important functions for telomere biology.
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Affiliation(s)
- Hiroto Izumi
- Department of Occupational Pneumology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Fukuoka 807-8555, Japan.
| | - Keiko Funa
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, SE-40530 Gothenburg, Sweden.
- Oncology Laboratory, University of Gothenburg, Sahlgrenska Hospital, Gula stråket 8, SE-41345 Gothenburg, Sweden.
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11
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Cyclooxygenase-2-Mediated Up-Regulation of Mitochondrial Transcription Factor A Mitigates the Radio-Sensitivity of Cancer Cells. Int J Mol Sci 2019; 20:ijms20051218. [PMID: 30862036 PMCID: PMC6429587 DOI: 10.3390/ijms20051218] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/22/2019] [Accepted: 03/07/2019] [Indexed: 12/23/2022] Open
Abstract
Mitochondrial transcription factor A (TFAM) regulates mitochondrial biogenesis, and it is a candidate target for sensitizing tumor during therapy. Previous studies identified that increased TFAM expression conferred tumor cells resistance to ionizing radiation. However, the mechanisms on how TFAM are regulated in irradiated tumor cells remain to be explored. In this research, we demonstrated the contribution of cyclooxygenase-2 (COX-2) to enhancing TFAM expression in irradiated tumor cells. Our results showed TFAM was concomitantly up-regulated with COX-2 in irradiated tumor cells. Inhibition of COX-2 by NS-398 blocked radiation-induced expression of TFAM, and prostaglandin E2 (PGE2) treatment stimulated TFAM expression. We next provided evidence that DRP1-mediated mitochondrial fragmentation was a reason for TFAM up-regulation in irradiated cells, by using small interfering RNA (siRNA) and selective inhibitor-targeted DRP1. Furthermore, we proved that p38-MAPK-connected COX-2, and DRP1-mediated TFAM up-regulation. Enhanced phosphorylation of p38 in irradiated tumor cells promoted DRP1 expression, mitochondrial fragmentation, and TFAM expression. NS-398 treatment inhibited radiation-induced p38 phosphorylation, while PGE2 stimulated the activation of p38. The results put forward a mechanism where COX-2 stimulates TFAM expression via p38-mediated DRP1/mitochondrial fragmentation signaling in irradiated tumor cells, which may be of value in understanding how to sensitize cancer cells during radiotherapy.
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12
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Lee WR, Na H, Lee SW, Lim WJ, Kim N, Lee JE, Kang C. Transcriptomic analysis of mitochondrial TFAM depletion changing cell morphology and proliferation. Sci Rep 2017; 7:17841. [PMID: 29259235 PMCID: PMC5736646 DOI: 10.1038/s41598-017-18064-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 12/05/2017] [Indexed: 12/27/2022] Open
Abstract
Human mitochondrial transcription factor A (TFAM) has been implicated in promoting tumor growth and invasion. TFAM activates mitochondrial DNA (mtDNA) transcription, and affects nuclear gene expression through mitochondrial retrograde signaling. In this study, we investigated the effects of TFAM depletion on the morphology and transcriptome of MKN45 gastric cancer cells. Morphology alteration became visible at 12 h after TFAM knockdown: the proportion of growth-arrested polygonal cells versus oval-shaped cells increased, reaching a half-maximum at 24 h and a near-maximum at 36 h. TFAM knockdown upregulated four genes and downregulated six genes by more than threefold at 24 h and similarly at 48 h. Among them, the knockdown of CFAP65 (cilia and flagella associated protein 65) or PCK1 (cytoplasmic phosphoenolpyruvate carboxykinase) rescued the effects of TFAM depletion on cell morphology and proliferation. PCK1 was found to act downstream of CFAP65 in calcium-mediated retrograde signaling. Furthermore, mtDNA depletion by 2',3'-dideoxycytidine was sufficient for induction of CFAP65 and PCK1 expression and inhibition of cell proliferation, but oxidative phosphorylation blockade or mitochondrial membrane potential depolarization was not. Thus, the TFAM-mtDNA-calcium-CFAP65-PCK1 axis participates in mitochondrial retrograde signaling, affecting tumor cell differentiation and proliferation.
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Affiliation(s)
- Woo Rin Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea
- Center for Bioanalysis, Korea Research Institute of Standards and Science, Daejeon, 34113, Korea
| | - Heeju Na
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea
| | - Seon Woo Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea
| | - Won-Jun Lim
- Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Korea
- Department of Bioinformatics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, 34141, Korea
| | - Namshin Kim
- Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Korea
- Department of Bioinformatics, KRIBB School of Bioscience, Korea University of Science and Technology, Daejeon, 34141, Korea
| | - J Eugene Lee
- Center for Bioanalysis, Korea Research Institute of Standards and Science, Daejeon, 34113, Korea.
| | - Changwon Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Korea.
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13
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Regulatory cis- and trans-elements of mitochondrial D-loop-driven reporter genes in budding tunicates. Mitochondrion 2017; 35:59-69. [PMID: 28526334 DOI: 10.1016/j.mito.2017.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 01/13/2017] [Accepted: 05/12/2017] [Indexed: 11/22/2022]
Abstract
To unveil the underlying mechanism of mitochondrial gene regulation associated with ageing and budding in the tunicate Polyandrocarpa misakiensis, mitochondrial non-coding-region (NCR)-containing reporter genes were constructed. PmNCR2.3K/GFP was expressed spatiotemporally in a pattern quite similar to mitochondrial 16SrRNA. The reporter gene expression was sensitive to high dose of rifampicin similar to mitochondrial genes, suggesting that the transcription indeed occurs in mitochondria. However, the gene expression also occurred in vivo in the cell nucleus and in vitro in the nuclear extracts. Mitochondrial transcription factor A (PmTFAM) enhanced reporter gene expression, depending on the NCR length. A budding-specific polypeptide TC14-3 is an epigenetic histone methylation inducer. It heavily enhanced reporter gene expression that was interfered by histone methylation inhibitors and PmTFAM RNAi. Our results indicate for the first time that the nuclear histone methylation is involved in mitochondrial gene activity via TFAM gene regulation.
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Lai WT, Li YJ, Wu SB, Yang CN, Wu TS, Wei YH, Deng YT. Connective tissue growth factor decreases mitochondrial metabolism through ubiquitin-mediated degradation of mitochondrial transcription factor A in oral squamous cell carcinoma. J Formos Med Assoc 2017; 117:212-219. [PMID: 28438434 DOI: 10.1016/j.jfma.2017.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 04/06/2017] [Accepted: 04/07/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND/PURPOSE Deregulation of metabolic pathways is one of the hallmarks of cancer progression. Connective tissue growth factor (CTGF/CCN2) acts as a tumor suppressor in oral squamous cell carcinoma (OSCC). However, the role of CTGF in modulating cancer metabolism is still unclear. METHODS OSCC cells stably overexpressing CTGF (SAS/CTGF) and shRNA against CTGF (TW2.6/shCTGF) were established. Oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were examined by the Seahorse XF24 analyzer. The expression of CTGF and mitochondrial biogenesis related genes was measured by real-time polymerase chain reaction or Western blot analysis. RESULTS CTGF decreased OCR, ECAR, adenosine triphosphate (ATP) generation, mitochondrial DNA (mtDNA), and mitochondrial transcription factor A (mtTFA) protein expression in OSCC cells. Overexpression of mtTFA restored CTGF-decreased OCR, ECAR, mtDNA copy number, migration and invasion of SAS/CTGF cells. Immunoprecipitation assay showed a higher level of ubiquitinated mtTFA protein after CTGF treatment. MG132, an inhibitor of proteasomal degradation, reversed the effect of CTGF on mtTFA protein expression in SAS cells. CONCLUSION CTGF can decrease glycolysis, mitochondrial oxidative phosphorylation, ATP generation, and mtDNA copy number by increasing mtTFA protein degradation through ubiquitin proteasome pathway and in turn reduces migration and invasion of OSCC cells. Therefore, CTGF may be developed as a potential additive therapeutic drug for oral cancer in the near future.
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Affiliation(s)
- Wei-Ting Lai
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Yue-Ju Li
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Shi-Bei Wu
- Institute of Biotechnology in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Cheng-Ning Yang
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Tai-Sheng Wu
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Yau-Huei Wei
- Institute of Biotechnology in Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Medicine, Mackay Medical College, Taiwan
| | - Yi-Ting Deng
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan; Department of Dentistry, National Taiwan University Hospital, Hsin-Chu Branch, Hsin-Chu, Taiwan.
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15
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MiR-199a-3p enhances breast cancer cell sensitivity to cisplatin by downregulating TFAM (TFAM). Biomed Pharmacother 2017; 88:507-514. [PMID: 28126676 DOI: 10.1016/j.biopha.2017.01.058] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 12/28/2016] [Accepted: 01/09/2017] [Indexed: 01/02/2023] Open
Abstract
Chemotherapy resistance is the major obstacle to the effective therapy of cancer. While the mechanism of chemotherapy resistance is still not fully understood. Increasing evidences demonstrated that microRNAs (miRNAs) may have a crucial function in chemotherapy resistance through modulating intracellular pathways. MiR-199a has been shown to be involved in multiple malignancy-related processes, although the precise mechanism is unclear at present. In this study, we found that the expression level of miR-199a-3p was lower in cisplatin (DDP) resistant breast cancer MDA-MB-231/DDP cells compared with parental DDP-sensitive cells. Inhibition of miR-199a-3p in MDA-MB-231 cells significantly attenuated DDP-induced apoptosis and anti-proliferative effects, while overexpression of miR-199a-3p in MDA-MB-231/DDP cells increased the sensitivity to DDP. Moreover, expression levels of mitochondrial transcription factor A (TFAM) were modulated by miR-199a-3p. The luciferase reporter assay indicated that TFAM may be the target gene of miR-199a. Knocking down of TFAM could partially reverse DDP resistance in MDA-MB-231 cells induced by miR-199a-3p inhibition, while TFAM overexpression could partially restore miR-199a-3p-induced chemo-sensitivity of MDA-MB-231/DDP cells to DDP. These results show that miR-199a-3p is able to attenuate cisplatin resistance in breast cancer cells through inhibiting TFAM expression.
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16
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Niemann J, Johne C, Schröder S, Koch F, Ibrahim SM, Schultz J, Tiedge M, Baltrusch S. An mtDNA mutation accelerates liver aging by interfering with the ROS response and mitochondrial life cycle. Free Radic Biol Med 2017; 102:174-187. [PMID: 27890640 DOI: 10.1016/j.freeradbiomed.2016.11.035] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 11/10/2016] [Accepted: 11/21/2016] [Indexed: 12/31/2022]
Abstract
Mitochondrial dysfunction affects liver metabolism, but it remains unclear whether this interferes with normal liver aging. We investigated several mitochondrial pathways in hepatocytes and liver tissue from a conplastic mouse strain compared with the control C57BL/6NTac strain over 18 months of life. The C57BL/6NTac-mtNODLtJ mice differed from C57BL/6NTac mice by a point mutation in mitochondrial-encoded subunit 3 of cytochrome c oxidase. Young C57BL/6NTac-mtNODLtJ mice showed reduced mitochondrial metabolism but similar reactive oxygen species (ROS) production to C57BL/6NTac mice. Whereas ROS increased almost equally up to 9 months in both strains, different mitochondrial adaptation strategies resulted in decreasing ROS in advanced age in C57BL/6NTac mice, but persistent ROS production in C57BL/6NTac-mtNODLtJ mice. Only the conplastic strain developed elongated mitochondrial networks with artificial loop structures, depressed autophagy, high mitochondrial respiration and up-regulated antioxidative response. Our results indicate that mtDNA mutations accelerate liver ballooning degeneration and carry a serious risk of premature organ aging.
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Affiliation(s)
- Jan Niemann
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany
| | - Cindy Johne
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany
| | - Susanne Schröder
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany
| | - Franziska Koch
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany; Institute of Nutritional Physiology "Oskar Kellner","Oskar Kellner", Leibnitz Institute for Farm Animal Biology, Dummerstorf, Germany
| | - Saleh M Ibrahim
- Institute of Experimental Dermatology, University of Lübeck, Lübeck, Germany
| | - Julia Schultz
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany
| | - Markus Tiedge
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany
| | - Simone Baltrusch
- Institute of Medical Biochemistry and Molecular Biology, University of Rostock, Rostock, Germany.
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Lionaki E, Gkikas I, Tavernarakis N. Differential Protein Distribution between the Nucleus and Mitochondria: Implications in Aging. Front Genet 2016; 7:162. [PMID: 27695477 PMCID: PMC5025450 DOI: 10.3389/fgene.2016.00162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/01/2016] [Indexed: 01/05/2023] Open
Abstract
The coordination of nuclear and mitochondrial genomes plays a pivotal role in maintenance of mitochondrial biogenesis and functionality during stress and aging. Environmental and cellular inputs signal to nucleus and/or mitochondria to trigger interorganellar compensatory responses. Loss of this tightly orchestrated coordination results in loss of cellular homeostasis and underlies various pathologies and age-related diseases. Several signaling cascades that govern interorganellar communication have been revealed up to now, and have been classified as part of the anterograde (nucleus to mitochondria) or retrograde (mitochondrial to nucleus) response. Many of these molecular pathways rely on the dual distribution of nuclear or mitochondrial components under basal or stress conditions. These dually localized components usually engage in specific tasks in their primary organelle of function, whilst upon cellular stimuli, they appear in the other organelle where they engage in the same or a different task, triggering a compensatory stress response. In this review, we focus on protein factors distributed between the nucleus and mitochondria and activated to exert their functions upon basal or stress conditions. We further discuss implications of bi-organellar targeting in the context of aging.
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Affiliation(s)
- Eirini Lionaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas Heraklion, Greece
| | - Ilias Gkikas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-HellasHeraklion, Greece; Department of Basic Sciences, Faculty of Medicine, University of CreteHeraklion, Greece
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18
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Cross Talk of Proteostasis and Mitostasis in Cellular Homeodynamics, Ageing, and Disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:4587691. [PMID: 26977249 PMCID: PMC4763003 DOI: 10.1155/2016/4587691] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/24/2015] [Accepted: 12/31/2015] [Indexed: 12/26/2022]
Abstract
Mitochondria are highly dynamic organelles that provide essential metabolic functions and represent the major bioenergetic hub of eukaryotic cell. Therefore, maintenance of mitochondria activity is necessary for the proper cellular function and survival. To this end, several mechanisms that act at different levels and time points have been developed to ensure mitochondria quality control. An interconnected highly integrated system of mitochondrial and cytosolic chaperones and proteases along with the fission/fusion machinery represents the surveillance scaffold of mitostasis. Moreover, nonreversible mitochondrial damage targets the organelle to a specific autophagic removal, namely, mitophagy. Beyond the organelle dynamics, the constant interaction with the ubiquitin-proteasome-system (UPS) has become an emerging aspect of healthy mitochondria. Dysfunction of mitochondria and UPS increases with age and correlates with many age-related diseases including cancer and neurodegeneration. In this review, we discuss the functional cross talk of proteostasis and mitostasis in cellular homeodynamics and the impairment of mitochondrial quality control during ageing, cancer, and neurodegeneration.
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19
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Targeting Mitochondrial Function to Treat Quiescent Tumor Cells in Solid Tumors. Int J Mol Sci 2015; 16:27313-26. [PMID: 26580606 PMCID: PMC4661878 DOI: 10.3390/ijms161126020] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/20/2015] [Accepted: 11/02/2015] [Indexed: 12/12/2022] Open
Abstract
The disorganized nature of tumor vasculature results in the generation of microenvironments characterized by nutrient starvation, hypoxia and accumulation of acidic metabolites. Tumor cell populations in such areas are often slowly proliferating and thus refractory to chemotherapeutical drugs that are dependent on an active cell cycle. There is an urgent need for alternative therapeutic interventions that circumvent growth dependency. The screening of drug libraries using multicellular tumor spheroids (MCTS) or glucose-starved tumor cells has led to the identification of several compounds with promising therapeutic potential and that display activity on quiescent tumor cells. Interestingly, a common theme of these drug screens is the recurrent identification of agents that affect mitochondrial function. Such data suggest that, contrary to the classical Warburg view, tumor cells in nutritionally-compromised microenvironments are dependent on mitochondrial function for energy metabolism and survival. These findings suggest that mitochondria may represent an “Achilles heel” for the survival of slowly-proliferating tumor cells and suggest strategies for the development of therapy to target these cell populations.
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20
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B7-H4 downregulation induces mitochondrial dysfunction and enhances doxorubicin sensitivity via the cAMP/CREB/PGC1-α signaling pathway in HeLa cells. Pflugers Arch 2015; 466:2323-38. [PMID: 24658911 DOI: 10.1007/s00424-014-1493-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 02/26/2014] [Accepted: 02/26/2014] [Indexed: 12/15/2022]
Abstract
B7-H4 is a B7 family coregulatory protein that inhibits T cell-mediated immunity. B7-H4 is overexpressed in various cancers; however, the functional role of B7-H4 in cancer metabolism is poorly understood. Because mitochondria play pivotal roles in development, proliferation, and death of cancer cells, we investigated molecular and functional alterations of mitochondria in B7-H4-depleted HeLa cells. In a human study, overexpression of B7-H4 was confirmed in the cervices of adenocarcinoma patients (n = 3) compared to noncancer patients (n = 3). In the cell line model, B7-H4 depletion was performed by transfection with small interfering RNA (siRNA). B7-H4 depletion suppressed oxygen consumption rate, ATP production, and mitochondrial membrane potential and mass and increased reactive oxygen species production. In particular, electron transport complex III activity was significantly impaired in siB7-H4-treated cells. Coincidently, depletion of B7-H4 suppressed major mitochondrial regulators (peroxisome proliferator-activated receptor gamma coactivator 1-alpha [PGC1-α] and mitochondrial transcription factor A), a component of oxidative phosphorylation (ubiquinol-cytochrome c reductase core protein 1), and an antiapoptosis protein (Bcl-XL). Mitochondrial dysfunction in siRNA-treated cells significantly augmented oxidative stress, which strongly activated the JNK/P38/caspase axis in the presence of doxorubicin, resulting in increased apoptotic cell death. Investigating the mechanism of B7-H4-mediated mitochondrial modulation, we found that B7-H4 depletion significantly downregulated the cAMP/cAMP response element-binding protein/PGC1-α signaling pathway. Based on these findings, we conclude that B7-H4 has a role in the regulation of mitochondrial function, which is closely related to cancer cell physiology and drug sensitivity.
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21
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Mitochondrial Transcription Factor A and Mitochondrial Genome as Molecular Targets for Cisplatin-Based Cancer Chemotherapy. Int J Mol Sci 2015; 16:19836-50. [PMID: 26307971 PMCID: PMC4581328 DOI: 10.3390/ijms160819836] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 07/28/2015] [Accepted: 08/07/2015] [Indexed: 12/30/2022] Open
Abstract
Mitochondria are important cellular organelles that function as control centers of the energy supply for highly proliferative cancer cells and regulate apoptosis after cancer chemotherapy. Cisplatin is one of the most important chemotherapeutic agents and a key drug in therapeutic regimens for a broad range of solid tumors. Cisplatin may directly interact with mitochondria, which can induce apoptosis. The direct interactions between cisplatin and mitochondria may account for our understanding of the clinical activity of cisplatin and development of resistance. However, the basis for the roles of mitochondria under treatment with chemotherapy is poorly understood. In this review, we present novel aspects regarding the unique characteristics of the mitochondrial genome in relation to the use of platinum-based chemotherapy and describe our recent work demonstrating the importance of the mitochondrial transcription factor A (mtTFA) expression in cancer cells.
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22
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Yamaguchi T, Kurita T, Nishio K, Tsukada J, Hachisuga T, Morimoto Y, Iwai Y, Izumi H. Expression of BAF57 in ovarian cancer cells and drug sensitivity. Cancer Sci 2015; 106:359-66. [PMID: 25611552 PMCID: PMC4409878 DOI: 10.1111/cas.12612] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 01/09/2015] [Accepted: 01/12/2015] [Indexed: 01/01/2023] Open
Abstract
The SMARCE1 (SWI / SNF-related, matrix-associated, and actin-dependent regulator of chromatin, subfamily e, member 1) encodes BAF57 protein. Previously, we reported that BAF57 is a predictive marker of endometrial carcinoma. In this study, we investigated BAF57 expression in ovarian cancer cell lines and their sensitivities to cisplatin, doxorubicin, paclitaxel, and 5-fluorouracil. BAF57 expression was strongly correlated with sensitivities to cisplatin, doxorubicin, and 5-fluorouracil in 10 ovarian cancer cell lines. Paclitaxel sensitivity was also correlated with BAF57 expression, but without significance. In A2780 ovarian cancer cells, knockdown of BAF57 using specific siRNA increased cell cycle arrest at G1 phase and the sensitivities to these anticancer agents. cDNA microarray analysis of A2780 cells transfected with BAF57 siRNA showed that 134 genes were positively regulated by BAF57, including ATP-binding cassette, sub-family G (WHITE), member 2 (ABCG2) encoding breast cancer resistance protein (BCRP). We confirmed that knockdown of BAF57 decreased BCRP expression in ovarian cancer cells by Western blot analysis, and that ABCG2 gene expression might be regulated transcriptionally. These results suggested that BAF57 is involved in ovarian cancer cell growth and sensitivity to anticancer agents, and that BAF57 may be a target for ovarian cancer therapy.
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Affiliation(s)
- Takahiro Yamaguchi
- Hematology, University of Occupational and Environmental Health, Kitakyushu, Japan
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23
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The Emerging Role of MitomiRs in the Pathophysiology of Human Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 888:123-54. [DOI: 10.1007/978-3-319-22671-2_8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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24
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Duarte FV, Palmeira CM, Rolo AP. The Role of microRNAs in Mitochondria: Small Players Acting Wide. Genes (Basel) 2014; 5:865-86. [PMID: 25264560 PMCID: PMC4276918 DOI: 10.3390/genes5040865] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/05/2014] [Accepted: 09/05/2014] [Indexed: 01/17/2023] Open
Abstract
MicroRNAs (miRNAs) are short, single-stranded, non-coding RNA molecules that act as post-transcriptional gene regulators. They can inhibit target protein-coding genes, through repressing messenger RNA (mRNA) translation or promoting their degradation. miRNAs were initially found to be originated from nuclear genome and exported to cytosol; where they exerted most of their actions. More recently, miRNAs were found to be present specifically in mitochondria; even originated there from mitochondrial DNA, regulating in a direct manner genes coding for mitochondrial proteins, and consequently mitochondrial function. Since miRNAs are recognized as major players in several biological processes, they are being considered as a key to better understand, explain, and probably prevent/cure not only the pathogenesis of multifactorial diseases but also mitochondrial dysfunction and associated diseases. Here we review some of the molecular mechanisms purported for miRNA actions in several biological processes, particularly the miRNAs acting in mitochondria or in mitochondria-related mechanisms.
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Affiliation(s)
- Filipe V Duarte
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-504, Portugal.
| | - Carlos M Palmeira
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-504, Portugal.
| | - Anabela P Rolo
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-504, Portugal.
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25
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Negative transcriptional regulation of mitochondrial transcription factor A (TFAM) by nuclear TFAM. Biochem Biophys Res Commun 2014; 450:166-71. [PMID: 24875355 DOI: 10.1016/j.bbrc.2014.05.082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 05/19/2014] [Indexed: 11/23/2022]
Abstract
The nuclear DNA-encoded mitochondrial transcription factor A (TFAM) is synthesized in cytoplasm and transported into mitochondria. TFAM enhances both transcription and replication of mitochondrial DNA. It is unclear, however, whether TFAM plays a role in regulating nuclear gene expression. Here, we demonstrated that TFAM was localized to the nucleus and mitochondria by immunostaining, subcellular fractionation, and TFAM-green fluorescent protein hybrid protein studies. In HT22 hippocampal neuronal cells, human TFAM (hTFAM) overexpression suppressed human Tfam promoter-mediated luciferase activity in a dose-dependent manner. The mitochondria targeting sequence-deficient hTFAM also repressed Tfam promoter activity to the same degree as hTFAM. It indicated that nuclear hTFAM suppressed Tfam expression without modulating mitochondrial activity. The repression required for nuclear respiratory factor-1 (NRF-1), but hTFAM did not bind to the NRF-1 binding site of its promoter. TFAM was co-immunoprecipitated with NRF-1. Taken together, we suggest that nuclear TFAM down-regulate its own gene expression as a NRF-1 repressor, showing that TFAM may play different roles depending on its subcellular localizations.
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26
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Yao J, Zhou E, Wang Y, Xu F, Zhang D, Zhong D. microRNA-200a Inhibits Cell Proliferation by Targeting Mitochondrial Transcription Factor A in Breast Cancer. DNA Cell Biol 2014; 33:291-300. [PMID: 24684598 DOI: 10.1089/dna.2013.2132] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Jia Yao
- Department of General Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Enxiang Zhou
- Department of General Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Yichun Wang
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, China
| | - Feng Xu
- Department of General Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Danhua Zhang
- Department of General Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Dewu Zhong
- Department of General Surgery, The Second Xiangya Hospital of Central South University, Changsha, China
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Yamauchi M, Nakayama Y, Minagawa N, Torigoe T, Shibao K, Yamaguchi K. Mitochondrial transcription factor a worsens the clinical course of patients with pancreatic cancer through inhibition of apoptosis of cancer cells. Pancreas 2014; 43:405-10. [PMID: 24622070 DOI: 10.1097/mpa.0000000000000049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Mitochondrial transcription factor A (mtTFA) is mandatory for both the transcription and maintenance of mitochondrial DNA. This study aimed to investigate the significance of mtTFA expression in pancreatic ductal adenocarcinoma (PDAC). METHODS Surgical specimens from 93 patients with PDAC who all underwent pancreatectomy were immunohistochemically stained using a polyclonal anti-mtTFA antibody. The relationship between the expression of mtTFA, clinicopathologic factors, and prognosis of these patients were evaluated. RESULTS Positive mtTFA expression was significantly associated with lymphovascular invasion and metastatic recurrence in the liver and correlated with an advanced surgical stage. A univariate analysis showed that the patients with positive mtTFA expression had a significantly shorter survival time than those patients with negative mtTFA expression, and a multivariate analysis revealed that mtTFA expression was one of the independent prognostic factors in patients with PDAC. Positive mtTFA expression was significantly correlated with a low apoptotic index but not significantly correlated with the mind bomb homolog-1 (MIB-1) index. CONCLUSIONS The expression mtTFA worsens the clinical course of patients with PDAC through the inhibition of apoptosis of PDAC cells and is an independent marker for the poor prognosis of the patients with PDAC after pancreatectomy. Mitochondrial transcription factor A may be a novel target for the treatment of PDAC.
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Affiliation(s)
- Masumi Yamauchi
- From the *Department of Surgery 1, School of Medicine, University of Occupational and Environmental Health, Yahata-nishi-ku; and †Department of Gastroenterological and General Surgery, Wakamatsu Hospital of University of Occupational and Environmental Health, Wakamatsu-ku, Kitakyushu, Japan
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28
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Stat3 binds to mtDNA and regulates mitochondrial gene expression in keratinocytes. J Invest Dermatol 2014; 134:1971-1980. [PMID: 24496235 PMCID: PMC4057971 DOI: 10.1038/jid.2014.68] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/26/2013] [Accepted: 11/05/2013] [Indexed: 11/24/2022]
Abstract
The nuclear transcription factor Stat3 has recently been reported to have a localized mitochondrial regulatory function. Current data suggest that mitochondrial Stat3 (mitoStat3) is necessary for maximal mitochondrial activity and for Ras-mediated transformation independent of Stat3 nuclear activity. We have previously shown that Stat3 plays a pivotal role in epithelial carcinogenesis. Therefore, the aim of the current study was to determine the role of mitoStat3 in epidermal keratinocytes. Herein, we show that normal and neoplastic keratinocytes contain a pool of mitoStat3. EGF and TPA induce Stat3 mitochondrial translocation mediated through phosphorylation of Stat3 at Ser727. In addition, we report that mitoStat3 binds mitochondrial DNA (mtDNA) and associates with the mitochondrial transcription factor TFAM. Furthermore, Stat3 ablation resulted in an increase of mitochondrial encoded gene transcripts. An increase in key nuclear-encoded metabolic genes, PGC-1α and NRF-1, was also observed in Stat3 null keratinocytes, however no changes in nuclear-encoded ETC gene transcripts or mtDNA copy number were observed. Collectively, our findings suggest a heretofore-unreported function for mitoStat3 as a potential mitochondrial transcription factor in keratinocytes. This mitoStat3-mtDNA interaction may represent an alternate signaling pathway that could alter mitochondrial function and biogenesis and play a role in tumorigenesis.
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Jiang J, Yang J, Wang Z, Wu G, Liu F. TFAM is directly regulated by miR-23b in glioma. Oncol Rep 2013; 30:2105-10. [PMID: 24002170 DOI: 10.3892/or.2013.2712] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 07/15/2013] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial transcription factor A (TFAM), a high-mobility group (HMG) protein, plays a central role in mitochondrial DNA (mtDNA) replication, transcription and inheritance. It has been shown that TFAM is associated with tumorigenesis. However, little is known regarding the posttranscriptional regulation of TFAM in glioma. In the present study, we found that the protein levels of TFAM were gradually increased, while the expression of miRNA-23b was gradually downregulated with the malignancy of glioma. Luciferase assay data demonstrated that miRNA-23b directly regulated TFAM. Furthermore, forced overexpression of miRNA-23b in U251 cells markedly inhibited the proliferation, cell cycle progression, migration and colony formation, while overexpression of TFAM significantly enhanced these biological processes. We further examined the related molecular mechanism, and found that the activity of the PI3K/Akt signaling pathway, critical for cell proliferation and migration, was suppressed in miRNA-23b-overexpressing U251 cells but was upregulated in TFAM-overexpressing cells. In addition, the expression levels of invasion-related MMP2 and MMP9 were decreased in miRNA-23b-overexpressing U251 cells but were increased in TFAM-overexpressing cells. Taken together, the present study provides a new regulatory mechanism as well as a promising therapy target for glioma.
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Affiliation(s)
- Jiaode Jiang
- Department of Neurosurgery, Third Xiangya Hospital of Central South University, Changsha, Hunan 410013, P.R. China
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30
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Mo M, Peng F, Wang L, Peng L, Lan G, Yu S. Roles of mitochondrial transcription factor A and microRNA-590-3p in the development of bladder cancer. Oncol Lett 2013; 6:617-623. [PMID: 24137381 PMCID: PMC3789041 DOI: 10.3892/ol.2013.1419] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 06/13/2013] [Indexed: 11/07/2022] Open
Abstract
Mitochondrial transcription factor A (TFAM) is required for mitochondrial DNA (mtDNA) replication and transcription. microRNAs (miRNAs) act as key factors in the regulation of gene expression. However, the roles of TFAM and certain miRNAs and their association in cancer development remain unclear. The present study reported that the expression of TFAM was significantly increased in bladder cancer, while the expression of miRNA-590-3p was downregulated. The luciferase assay showed that TFAM was the direct target of miRNA-590-3p. Furthermore, the forced overexpression of miRNA-590-3p significantly inhibited the proliferation, migration and colony-forming ability of 5637 cells, which was in contrast with the results from the forced overexpression of TFAM in the 5637 cells. Furthermore, cell proliferation- and migration-related genes, including phosphoinositide-3-kinase (PI3K), Akt, matrix metalloproteinase (MMP)-2 and MMP9, were significantly downregulated in the miRNA-590-3p-overex-pressing 5637 cells, but upregulated in the TFAM-overexpressing cells. In conclusion, the present study suggested that TFAM, a direct target of miRNA-590-3p, may play a significant role in the tumorigenesis of bladder cancer and thus may be a promising target for cancer therapeutics.
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Affiliation(s)
- Miao Mo
- Department of Urologic Organ Transplantation, The Second Xiangya Hospital of Central South University, Changsha, Hunan, P.R. China
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31
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Dynamic localization of two tobamovirus ORF6 proteins involves distinct organellar compartments. J Gen Virol 2013; 94:230-240. [DOI: 10.1099/vir.0.045278-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ORF6 is a small gene that overlaps the movement and coat protein genes of subgroup 1a tobamoviruses. The ORF6 protein of tomato mosaic virus (ToMV) strain L (L-ORF6), interacts in vitro with eukaryotic elongation factor 1α, and mutation of the ORF6 gene of tobacco mosaic virus (TMV) strain U1 (U1-ORF6) reduces the pathogenicity in vivo of TMV, whereas expression of this gene from two other viruses, tobacco rattle virus (TRV) and potato virus X (PVX), increases their pathogenicity. In this work, the in vivo properties of the L-ORF6 and U1-ORF6 proteins were compared to identify sequences that direct the proteins to different subcellular locations and also influence virus pathogenicity. Site-specific mutations in the ORF6 protein were made, hybrid ORF6 proteins were created in which the N-terminal and C-terminal parts were derived from the two proteins, and different subregions of the protein were examined, using expression either from a recombinant TRV vector or as a yellow fluorescent protein fusion from a binary plasmid in Agrobacterium tumefaciens. L-ORF6 caused mild necrotic symptoms in Nicotiana benthamiana when expressed from TRV, whereas U1-ORF6 caused severe symptoms including death of the plant apex. The difference in symptoms was associated with the C-terminal region of L-ORF6, which directed the protein to the endoplasmic reticulum (ER), whereas U1-ORF6 was directed initially to the nucleolus and later to the mitochondria. Positively charged residues at the N terminus allowed nucleolar entry of both U1-ORF6 and L-ORF6, but hydrophobic residues at the C terminus of L-ORF6 directed this protein to the ER.
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32
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Abstract
Contrary to conventional wisdom, functional mitochondria are essential for the cancer cell. Although mutations in mitochondrial genes are common in cancer cells, they do not inactivate mitochondrial energy metabolism but rather alter the mitochondrial bioenergetic and biosynthetic state. These states communicate with the nucleus through mitochondrial 'retrograde signalling' to modulate signal transduction pathways, transcriptional circuits and chromatin structure to meet the perceived mitochondrial and nuclear requirements of the cancer cell. Cancer cells then reprogramme adjacent stromal cells to optimize the cancer cell environment. These alterations activate out-of-context programmes that are important in development, stress response, wound healing and nutritional status.
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Affiliation(s)
- Douglas C Wallace
- Children's Hospital of Philadelphia, Center for Mitochondrial and Epigenomic Medicine, Philadelphia, Pennsylvania 19104, USA.
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33
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Chen Y, Liu J, Yuan B, Cao C, Qin S, Cao X, Bian G, Wang Z, Jiang J. Methylated actinomycin D, a novel actinomycin D analog induces apoptosis in HepG2 cells through Fas- and mitochondria-mediated pathways. Mol Carcinog 2012; 52:983-96. [DOI: 10.1002/mc.21943] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 05/11/2012] [Accepted: 06/26/2012] [Indexed: 01/15/2023]
Affiliation(s)
- Yongqiang Chen
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Jinjuan Liu
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Bo Yuan
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Chengliang Cao
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Sheng Qin
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Xiaoying Cao
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Guangkai Bian
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Zhe Wang
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
| | - Jihong Jiang
- Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province; Xuzhou Normal University; Xuzhou China
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34
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Abstract
It is well known that remnants of partial or whole copies of mitochondrial DNA, known as Nuclear MiTochondrial sequences (NUMTs), are found in nuclear genomes. Since whole genome sequences have become available, many bioinformatics studies have identified putative NUMTs and from those attempted to infer the factors involved in NUMT creation. These studies conclude that NUMTs represent randomly chosen regions of the mitochondrial genome. There is less consensus regarding the nuclear insertion sites of NUMTs - previous studies have discussed the possible role of retrotransposons, but some recent ones have reported no correlation or even anti-correlation between NUMT sites and retrotransposons. These studies have generally defined NUMT sites using BLAST with default parameters. We analyze a redefined set of human NUMTs, computed with a carefully considered protocol. We discover that the inferred insertion points of NUMTs have a strong tendency to have high-predicted DNA curvature, occur in experimentally defined open chromatin regions and often occur immediately adjacent to A + T oligomers. We also show clear evidence that their flanking regions are indeed rich in retrotransposons. Finally we show that parts of the mitochondrial genome D-loop are under-represented as a source of NUMTs in primate evolution.
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Affiliation(s)
- Junko Tsuji
- Department of Computational Biology, Graduate School of Frontier Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
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35
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Xiong W, Jiao Y, Huang W, Ma M, Yu M, Cui Q, Tan D. Regulation of the cell cycle via mitochondrial gene expression and energy metabolism in HeLa cells. Acta Biochim Biophys Sin (Shanghai) 2012; 44:347-58. [PMID: 22343378 DOI: 10.1093/abbs/gms006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human cervical cancer HeLa cells have functional mitochondria. Recent studies have suggested that mitochondrial metabolism plays an essential role in tumor cell proliferation. Nevertheless, how cells coordinate mitochondrial dynamics and cell cycle progression remains to be clarified. To investigate the relationship between mitochondrial function and cell cycle regulation, the mitochondrial gene expression profile and cellular ATP levels were determined by cell cycle progress analysis in the present study. HeLa cells were synchronized in the G0/G1 phase by serum starvation, and re-entered cell cycle by restoring serum culture, time course experiment was performed to analyze the expression of mitochondrial transcription regulators and mitochondrial genes, mitochondrial membrane potential (MMP), cellular ATP levels, and cell cycle progression. The results showed that when arrested G0/G1 cells were stimulated in serum-containing medium, the amount of DNA and the expression levels of both mRNA and proteins in mitochondria started to increase at 2 h time point, whereas the MMP and ATP level elevated at 4 h. Furthermore, the cyclin D1 expression began to increase at 4 h after serum triggered cell cycle. ATP synthesis inhibitor-oligomycin-treatment suppressed the cyclin D1 and cyclin B1 expression levels and blocked cell cycle progression. Taken together, our results suggested that increased mitochondrial gene expression levels, oxidative phosphorylation activation, and cellular ATP content increase are important events for triggering cell cycle. Finally, we demonstrated that mitochondrial gene expression levels and cellular ATP content are tightly regulated and might play a central role in regulating cell proliferation.
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Affiliation(s)
- Wei Xiong
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming, China
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Kurita T, Izumi H, Kagami S, Kawagoe T, Toki N, Matsuura Y, Hachisuga T, Kohno K. Mitochondrial transcription factor A regulates BCL2L1 gene expression and is a prognostic factor in serous ovarian cancer. Cancer Sci 2011; 103:239-444. [PMID: 22098591 DOI: 10.1111/j.1349-7006.2011.02156.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial transcription factor A (mtTFA) is necessary for both transcription and maintenance of mitochondrial DNA (mtDNA). Recently, we reported that mtTFA is expressed not only in mitochondria, but also in nuclei. However, the function of mtTFA in the nucleus has not been clearly elucidated. In the present study, we examined nuclear mtTFA expression in 60 tissue samples of serous ovarian cancer using immunohistochemical analysis and found that 56.7% of serous ovarian cancer patients were positive for mtTFA, whereas 43.3% were negative. Univariate survival analysis showed that the overall 5-year survival rate was significantly worse for patients with mtTFA-positive cancer compared with mtTFA-negative cancer (32%vs 42%, respectively; P = 0.021). To elucidate the function of mtTFA in the nucleus, we investigated BCL2L1, a target gene of mtTFA. There was a significant correlation between nuclear mtTFA expression and BCL2L1 expression in seven ovarian cancer cell lines and in specimens of clinical ovarian cancer. Cellular BCL2L1 was downregulated following transfection of siRNA against mtTFA. BCL2L1 promoter activity was increased after transfection of mtTFA expression plasmid, but decreased after siRNA knockdown of mtTFA. Chromatin immunoprecipitation assays showed that mtTFA was bound to the BCL2L1 promoter region. These results suggest that mtTFA is a prognostic factor for a poor outcome of ovarian cancer and may function as an antiapoptotic factor, regulating genes such as BCL2L1. Furthermore, mtTFA may be a promising molecular target for novel therapeutic strategies for the treatment of ovarian cancer.
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Affiliation(s)
- Tomoko Kurita
- Departments of Obstetrics and Gynecology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan
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